Controlled humidity refrigerator



Feb. 25, 1947.

M. G. SHOEMAKER CONTROLLED HUMIDITY REFRIGERATOR 2 Sheets-Sheet Ll. F/QZFiled March 29, 1944 F 25, 19475 M. e. SHOEMAKER v CONTROLLED HUMIDITYREFRIGERATOR '2 Sheets-Sheet 2 Filed March 29, 1944 Patented Feb. 25,1947 CONTROLLED HUMIDITY REFRIGERATOR Malcolm G. Shoemaker, Abington,Pa., assignor, by mesne assignments, to Phllco Corporation,

Philadelphia, Pa, vania a corporation of Pennsyl- Application March 29,1944. Serial No. 528,581

1 This invention relates to refrigeration apparatus, and is particularlyconcerned with re- 9 Claims. (Cl. 62-6) frigerators which include a highhumidity compartment especially adapted 'to preserve foodstuffs withoutdehydration thereof. The invention has especial reference to suchrefrigerators, in which the compartment air is forcibly circulated inheat exchange relation with an evaporator.

More specifically, the present invention has reference to refrigeratorsof the multiple temperature type in which the temperature of the air inthe main food storage compartment is maintained above that existing inother portions of the box, andthe relative humidity in said compartmentis at a high value.

In such apparatus, it has proven difllcult to insure the desired degreeof humidity throughout A further object of the invention resides in theprovision of a refrigeration apparatus, in which circulating airprovides heat'transfer capacity additional to that effected through thewalls of the food storage compartment.

It is also an object of the invention to provide a refrigerator in whichundesired moisture is removed from the cabinet air without causing theaccumulation of frost in any portion of the refrigerating system.

Broadly, the present invention provides a refrigerator having aplurality of zones maintained at moist-cold," sharp-freeze andintermediate temperatures respectively, in accordance with therequirements of various foodstuffs to be preserved therein; while a morespecific object of the inall seasons of the year, while preventing thehumidity from reaching undesirably high values at certain times, andparticularly in damp climates. Proper humidity control is-particularlyimportant, in view of the fact that cooling of the "moist-coldcompartment is customarily accomplished by effecting the necessary heattransfer through the walls of said compartment. method of heat transferhas certain evident ad vantages, such for example, as affording a foodcompartment which is clear and unobstructed, but these advantages neednot be considered in detail here. Efiecting the cooling in the abovementioned manner results in maintenance of the temperature of thecompartment walls at a value well below the dew point temperature of theair in said compartment at the high relative humidity customarilyexisting in the latter. As a consequence, excessively high humidity pro-This duces undesirable condensation upon the walls. 7

By the present invention, the difliculties and ob- Jections previouslyencountered are eliminated and, to this end, it is a primary object ofthis invention to provide a refrigerator having novel means forcontrolling the humidity conditions therein, and for decreasing theaverage temperature differential between the air within the compartmentand the walls thereof.

More particularly, it is an object of the present invention to provide arefrigeration apparatus having novel means for removing moisture fromthe cabinet air, as and when required, and for lowering the temperatureof said air with respect to that of the wall structure.

To this end, the invention contemplates the provision ofhumidity-responsive means for withdrawing air from the food compartment,passing it in heat exchange relation with a cold zone and re-injectingit into the compartment after its temperature has been reduced and afterthe desired degree of moisture has been removed therevention resides inthe provision of such refrigeration apparatus, having a.moisture-removing evaporator portion which affords heat transfercapacity in addition to that supplied by the evaporator arranged to coolthe walls of the main food storage compartment.

These and other objects and advantages of the invention may be moreclearly understood by reference to the following description and to theaccompanying drawings in which:

Fig.1 is an elevational and partial sectional view of a refrigeratorembodying the invention,

the refrigerator being shown with the main food I compartment doorremoved therefrom;

Fig. 2 is a sectional view taken on the line 2-4 of'Fig. 1, and with themain door included in the assembly;

,Fig. 3 is an enlarged perspective view from therear of the refrigeratorinner tank structure, certain portions being broken away for the sake ofclarity in illustration;

Fig. 4 is an enlarged sectional view taken on the line 4-4 of Fig. 1; i

Fig; 5 is an enlarged sectionalview taken on the line 5-5 of Fi 2; and

Fig. 6 is an enlarged sectional illustration of a detail of theconstruction. a

In Figs. 1 and 2 of the drawings, there is illustrated a domesticrefrigerator of the mechanical type which includes an outer shell 3,which may.

be of any well-known type and construction, and an inner metal shell orliner member 4 providing the, main food storage space, indicatedgenerally at 5. This space 5 is fitted with a plurality of shelves 6, ofany desired type. Vertical and horizontal breaker strips 1 and 8,respectively, of low thermal conductivity, are fitted around the forwardmarginal edge of the cabinet opening,

while thermal insulation, portions of which are indicated at 9,completely surrounds the inner liner member 4 as well as the outsidesurfaces of the cooling means presently to be described. The

cabinet is provided with a door I0, said door being adapted to seatthereagainst in the plane .0: the reaker'strips and flpasillustrated myJ A machinery compartment ii is located in the ,lower portion of thecabinet structure, which; 4 compartment houses the compressor unitindicated generally at l2; The main, sharp-freezing evaporator-"storagesection is shown at I! and includes, generally,- a relatively largewell-typey,

storage area H,- to which. access maybe had.

through. a door l5, and a smallerice-freezing f space indicated at [8.Thisevaporator may be supported within the refrigerator in any con-1venient manner, as for example, by welding its-I outer vertical walls toan inturned flange formed about the lower edges of the inner liner 4.Cer-- M tainfeatures' of the particular evaporator 1111139. trated,- aredisclosed and claimed. in. the co- 1S pend ng application of Donald E.Dailey','seriall No 515,950, flied December 28,. 1943, anda's suchfeatures, per se, form no part of the present invention, detaileddescription thereof' is not deemednecessaryrc i v k:Intheembodimentillustrated, and as best 'seenin Figs. 2 and 4; adouble-thickness insulat ing partition- I! provides the floor for themain storage compartment 5; this partition being in-'" terposed betweenthemainevaporatorsectionst 1 and the storage compartment 5, in ordertomake it possible tooperate said compartment at rela-'-' tivelyhightemperaturesas compared with the temperature of 'thev evaporatorsections it andj l8, and to prevent the undesired frosting-out or; Imoisture present in said compartment}. As clearlyappears in Fig, 4,!gasket members)": i 1 surround the partition i1, said gaskets beingin'-' terposedbetween the partition members and the adjacent wallportions of the inner liner 4, ,e Referring to Fig. 3, it will be seenthat the main cuitrwillhave 'a capacity: whi h more h sufficient tomeetthe maxmum heat load con dition which may be encountered inpractice, dur-' ing' the different cycles of operation presently-tebedescribed.

- It should be'borne in. mind that the inven-{J tionis particularlyconcerned with an arrangement in which the major portion of thecooling-j f. "of the main food storage compartment 5 isac- 'complishedthrough the medium of the secondary "I v 1 tubing l9; while additionalheat transfer capacity'is provided and the elimination of desiredhumidity from said compartment is ac- I complished by effecting periodiccirculation 'of compartment air through the several ducts ap-Yl pearingin Fig. 3,-and thence into the passage.

28. arranged iniheat exchange relation'with the.

primary 'evaporator tubing At; this 'pointgflu there is a transfer oflatent heat from the moisture-laden air to the low temperature tub-f ing25 and, consequently, some of the moisture is a condensed upon thesurrounding'surfaces. Fol-llowing this,'the air whoseabsolutehumidityhas;- -.nowbeen substantially decreased, is re-injected into thefood storage-compartment, and, combining with the air. in saidcompartment,- acts to. lower'the overall relative humidity therein Thiscirculation is effected, as and when required by means of a motor andassociated fan 3i 3 operable periodically in response to the humidity 1In the embodiment'illustrated, this controlled" i circulation isinitiated by a humidostat 32 (see. Figs. 1 and 2) which may be of anydesired type. I Since the invention is not concerned with the.

conditions existing in the'compartment I. I

-. particular humidostat employed, a description of foodstoragesection Bis cooled, primarily, by

means of tubing 19 secured in convoluted ar 3 rangement about theexterior surface of the inner linen-andconstituting the-evaporatorportion of" a secondary, refrigerant circuit of known type.

' the details thereof is not necessary herein. However, it willbeunderstood that the humidostat is adapted to initiate operation of themotor 30%;

when the relative humidity in compartment i-has risen'to a point justabove a predetermined value. 1 Further, while .humidostat control isPreferably employed, it. will be evident that it would be 7 possibietoeffect periodic actuation ofthe air which constitutes a series-connectedportion of a f the main primary circuit utilized to effect refriserationof thesharri-freezin; compartments H and IS. A detailed description ofthis portion of the apparatus is not necessary herein, since theinvention is not concerned therewith. QAlthough any convenient form ofprimary re- 1 0' frigerant circuit may be employed, there has been 1illustrated an arrangement in which (referring g to Figsrl to 3) theliquid refrigerant formed in the condenser 2l is delivered to-a centralshelf .j 22, in-the ice freezing compartment, said delivery p 1 beingeffected through a capillarytube 23 arranged in heat exchange relationwith the suction 1 line 24. From the entry point 230, the volatilerefrigerant is deliveredfto passages 26 arranged F about evaporatorstorage section l3, after which it flows through a lower passof tubing28 (see Fig. 4) and is delivered tothe small auxiliary evaporatorelement 20 by means of an'upwardly 5 extending conduit 21. After beingpassed in heat exchange relation with the refrigerant of the secondarysystem, the primary refrigerant is returned to the compressor unitthrough the down wardly extending suction conduit shown at in Figs.- 1and 3. It should beobserved that the lower pass of tubing 25, referred.to above, is arranged in closeproximity to an airflow passage 28, to bedescribed in greater detail hereinafter.

It is assumed, of course, that the primary circirculationfan by othermeans. For example, i

the motor- 80 could be energized at periodic.

timed intervals, in accordance with average humidity conditions found inpractice in anyplac ticular locality, With such an embodiment, thedevice 32 should be understood as representing an automatic timingdevice of any desired known form. While such operation would not resultin .as high 'a degree of control of the relative humidity as can beobtained by the use of a humidostat, it would be possible to prevent theexistence of undesirably high humidity conditions without causing thehumidity in the refrigerator to dropbelow a desired minimum. This willbe apparent from the fact that ii, for example, the passage i 28 ismaintained at a mean temperature of 33 F., 1 l (which will create acondition of IOU-percent relative humidity at 33,if condensation is.occurring) the air would be re-iniected into the compartment atapproximately 72 relative humidity, at the 40 F. temperature preferablymaintained in said compartment. under certaincircumstances, be desirableto circulate the compartment air even if the conditions were not suchthat condensation would occur in the passage 28, and such circulation isalso con.- templated by'the present invention.

Referring now with more particularity to the construction and operationof the air circulation apparatus, it will appear that the duct work, seefor example the passage 29, preferably comprises It might. I

a passage of airfrom structure 42- secured -iri-air-itight, arrangemen 1with section," of theyprimary evaporator, as by A means of the; flangesshown at flax As appears half-round tubing securedftol fllel mrdfm:cfliner .4, by. means of flanges .llyyvhi h may,

1' bonded to said wall in any convenientigmanner A horizontalair-withdrawal duct-r-ll4 f extends v across a Substantial portion ofthe-width "of liner;

4, in the lower porti 'nthereof; and as appears v in Figs. 1 and 2,- anaperture fl'is'provide'd in back "ofthe'upper portion of. the linermember:'-;

the liner wall beinzapertured at TI, to permi compartm l? Extendingdownwardly iii-anthe in a e-allay 34, is a short connection ductllwhich,' as may; be seen from'a'comparison of Figs: 3.and 8,, is-incommunication with a generally L-shaped saddl defines the passage 28 isdividedintoiniiow and" outflow sections 39 and"; respectively. by means:of a partition membershownatllt Referenceto Figs. 3, A} and 5-willshowthat-thefan li-is inf communication with outflow section 40, whilethe'downwardly exten'ding' ductiil isqin free com j munication'withthqinflOW-RElQn19p-f; The air flow isdesignated by arrows'a .in thedrawingsififrom 'whichfit willb'e' apparentthat" air is 'withdrawnEfrom'the compartment? through vduct 34, passes downwardly .into (the.

inflow section}! ofsaddle structure 42, thence. forwardly through saidsadd1e structure, around the forward end of partition 4| (as best seenin Fig. 4) and thence-throughoutflow portion 40 .and the blower unit ll.From this point, the air is directed upwardly through the verticalpassage a 29, from whence it is delivered toduct fl'forreinjectioninto'the main food storage compart ment. .-As appears in Fig. 5, aplurality of 43 depend from the supporting plate 44, said'flns-f' Fserving to promote heat transfer between the air When the fan acondition of excessive humidity in ,the compart ment 5, the invention,contemplates the main- ,tenance' ofv the, temperature of .air;passingthrough the inflow and outflow channels at a' This is temperatureabove the freezing point.

said duct-so; into the food" operation,

' the liner wall intre istr with duct portion'. A similar air injectionduct 38. extends across theso most clearly in Fig; 3,1111; saddlestructurewmch v desirable in order that the moisture condensed at I thispoint will not be frozen and thereby restrict the passage area,and'to'this end, a sheet of in-v sulating material 45 is preferablyinterposed bepassages; As will now be evident, the moving air below thedew point, and the resulting condensate tween the tubing 25 and saidinflow and outflow gives up if portion of its heat to'the tubing 28,thereby'reducing the temperature of said air surface, it isposslbl tfrosting zones within the winger-am; hydration ofs. therefore-prevented,

compartment air is then caused to circulatein heat, exchange relationwith the primary evaporator tubing 28 and is re-injected into therefrigshownby theair flow indications on the drawings 1. v v 31ml Thisair circulation is continued until suflicie'nt percentage of relativehumidity iii-compartment the motor circuit. -i a I theforegoingdescriptiomit will be understood"thatthetinvention provides a"refrigerato'r having a-novel. itygcont'r'ol meansr 7 ing -air'is'cooled'vduring the circulating process additional tothat' tubing whichis refrigerating the -compartment through the walls thereof;

" Further, this humidity control is effected with-i out attendantundesirable frosting, .and by an arrangement which lends itself well tothe usage I of a plurality of zones maintainedat temperatures berefrigerated. a

v rying in accordance with the demands of the variousfoodstuifs to 1claim: i I, 1.,In a. refrigerator having a walled portion defining ahigh humidity food storage compartto maintain said compartment atnon-frosting temperatures, second cooling' means providing heat transfercapacity in addition to'that provided by said first cooling means, andmeans rev sponsive to humiditycondition within said oompartment foreffecting intermittent forced circulation of thecompartment air in heatexchange relation with said second cooling means to condense moisturefrom saidair and to cause the temperature of the air in said compartmentto flows to a sump or trap 48' formed in the rear portion' of outflowsection 40. From this sump the liquid is delivered through pipe 41 intoa recep- Y tacle (not shown) which is preferably'in association with thecompressor unit II, in order that the condensate may be evaporated bythe heat of said unit, and in addition, may provide cooling fortheunit.4 l" Under normal conditions of operatiomi'. te., when the relativehumidity in compartment I is below a desired predetermined maximum, thefan Si is not in operation and the storage compartment is cooled solelyby the secondary tubing I! arranged about the liner walla. Sincesumcient approach that of the walls thereof.

-, 2.- In a refrigeratorhaving a walled portion I r defining a highhumidity food storageccmparh. I

ment, first coolingmeans in heat exchange relation with walls of thecompartment and comprising a volatile refrigerant system, adapted to Imaintain said compartment at non-frosting temperatures', second coolingmeans comprising a J I volatile refrigerant system providing heattrans-v fer capacity in addition to that provided by said' first coolingmeans, and means for effecting controlled forced circulation of thecompartment air in heat exchange relation with said second coolingmeans.

3.'In a refrigerator having a walled portion tubing is used to present alarge heat exchange I5 defining a high humidity food storage oompart-.

maintain compartment B at relatively lowtemperatures, for example in"the neighborhood Mail-40'1" without creatingthe foods within .lthecompartment T However,- should the humidity rise to an undesirably high,value, whichtmay occur very 'fre- H quently in certain climatelithehumido'stat u 'willrespond' thereto and initiate operation ofthe-motor}! audits associated blower. .i'lhe orator: 'intthe'manner'previously described, and

moisture'has been removed in the passages of the I saddle-like,structure 42, to restore ,the",-desired I, vatwhich time the humidostatdisconnectdladvantageous humid- I It is particularly'to'benotedthatthecirculatby -an.zevaporator having heat transfer capacity thereby notonlyfurther cooling the compartment as a whole,-but aso reducing the airtemperature with respect toth'at off the walls. This latter I effect, aswillnow' be. understood, minimizes the tendency oiwthe free moisture todeposit upon 'said walls.,.I. i C

ment, first cooling means in heat exchange rela-. tion with walls of thecompartment and adapted ment, a secondary refrigeration system includingan evaporator in heat exchange relationwith walls of the compartment andadapted to maintainsaid compartment at non-frosting temperatures, aprimary refrigeration system having ,a

portion thereof arranged in heat exchange rela tion with a portion ofsaid secondary system, said value and is adapted to maintain saidcirculation until the relative humidity is reduced to said predeterminedvalue. 5. In a refrigerator having a walled portion defining a highhumidity food storage compartment, a secondary refrigeration systemincluding an evaporator in heat exchange relation with walls of thecompartment and adapted to maintain said compartment at non-frostingtemperatures, a primary refrigeration system having a portion thereofarranged in heat exchange relation-with a portion of said secondarysystem, said primary system inciuding an evaporator having an airflowpassage in heat exchange relation therewith, means responsive tohumidity condition within said compartment for effecting intermittentforced circulation of the compartment air through said passage in heatexchange relation with said primary evaporator to condense moisture fromsaid air and to cause thetemperature of the air in said compartment toapproach that of the walls thereof, and means limiting the temperaturereduction effected in said passage to a value above the freezing pointof water.

6. In a refrigerator having a walled portiondeflning a high humidityfood storage comparttion with walls of the compartment and comprising avolatile refrigerant system adapted to maintain said compartment atnon-frosting temperatures, second cooling means comprising a volatilerefrigerant system including an evaporator adapted to operate attemperatures below those prevailing in said compartment and having anairflow passagein heat exchange relation therewith, means responsive tohumidity condition within said compartment for effecting intermittentforced circulation of the compartment air through said passage in heatexchange relation with said evaporator to condense moisture from saidair and to cause the temperature of the air in said compartment toapproach that of the walls thereof, and means limiting the temperaturereduction effected in said passage to a value above the freezing pointof water. i

7. In a refrigerator having a walled portion defining a high humidityfood storage compartment, first cooling means in heat exchange relationwith walls of the compartment and comprising a volatile refrigerantsystem adapted to ment, first cooling means in heat exchangerelamaintain said compartment at non-frosting temperatures, secondcooling means comprising a volatile refrigerant system including anevaporator adapted to operate at temperatures below those prevailing insaid compartment and having an airflow passage in heat exchange relationtherewith, means responsive to humidity condition within saidcompartment for effecting intermittent forced circulation of thecompartment air through said passage in heat exchange relation with saidevaporator to condense moisture from said air and to cause thetemperature of theair in said compartment to approach that of the wallsthereof, and insulation means interposed between said evaporatorand saidpassage and limiting the temperature reduction effected in the passageto a value above the freezing point of water.

8. A refrigerator comprising a plurality of refrigerated zones, oneof'which is adapted to be maintained at a condition of high relativehumidity, cooling means comprising a volatile refrigerant evaporatoradapted to maintain said one zone at a non-frosting temperature andcreating within the zone an area maintained at a temperature below thatof the air in said zone,

cooling means comprising a volatile refrigerant evaporator adapted tooperate at a temperature below that prevailing at any location in saidone zone, and arranged to cool another of said zones, means foreffecting forced circulation of air from said one zone in heat exchangerelation with said second-mentioned cooling means, and means forcontrolling the operation of said air circulating means, said last meansbeing adapted to initiate operation of said air circulating means uponthe relative humidity in said one zone exceeding a predetermined value.

9. A construction in accordance with claim 8, in which saidsecond-mentioned cooling means is adapted to operate at a sub-freezingtemperature and in which construction there is included an airflowpassage in heat exchange relation with said second mentioned coolingmeans through which the circulating air is passed, the arrangementfurther being characterized in that the heat exchange relation betweensaid passage and said cooling means is such as to limit reduction of theair temperature to a value above the freezing point of water.

' MALCOLM G. SHOEMAKER.

REFERENCES CITED The following references are of record-in the

